@book { MultinationaleUnternehmenVertikaleversushorizontaleIntegration,
    title = "Multinationale Unternehmen: Vertikale versus horizontale Integration",
    author = "Kai {Bergmaier}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836606226",
    url = "https://m.diplom.de/document/225418"
}